In cellular telecommunications networks, data communications between multiple mobile devices and the network are typically coordinated by a scheduler, which is conventionally comprised within the base station of the access portion of the network. Generally, each base station corresponds to a cell of the network and serves a geographical area. The term cell refers to a region in which radio signals from a specific base station antenna dominate. Each data transmission is divided into a set of data blocks, or resource blocks, which are transmitted in both the downlink (DL) and uplink (UL) directions, that is, from or to the base station. The scheduler assigns at which time these blocks are transmitted and assigns a ‘resource’ to be used for the transmission. A resource is a frequency of available spectrum which is to be used for that transmission. Hence a resource block is a time period of a particular frequency or set of frequencies which is to be used for transmission of a portion of the data.
In advanced telecommunications networks, Quality of Service (QoS) plays a key role in providing satisfactory service to users and in managing network functions. QoS is an indicator of the ability, or probability, of the network to provide a level of service for selected traffic on the network. Different service levels are specified for different types or streams of traffic. Typically, to provide QoS, the network identifies different types of streams of traffic and processes these traffic classes differently to achieve, or attempt to achieve, the desired service level for each traffic class.
In Long Term Evolution (LTE), for example, there are two types of traffic, those designated Guaranteed Bit Rate (GBR) and those designated non-Guaranteed Bit Rate (non-GBR). The GBR is the minimum reserved traffic rate the network guarantees. Those services designated as GBR services are allocated the highest priority and are allocated above all others when the base station allocated resource blocks for transmission.
Typically, cells of the network employ inter-cell interference coordination (ICIC) to assign resource blocks to the mobile devices. As part of this coordination, those cells serving adjacent or overlapping geographical areas, will share information with others to aid in serving those users who are situated at the edge of the geographical area covered by the cell, that is, those users which are likely to encounter interference from the use of resources by neighbouring cells. The available resource blocks are divided up between the two cells, such that the two cells assign sufficiently different resource blocks when serving users in proximity to each other. Thus, the risk of interference affecting transmissions for users in these locations is mitigated. ICIC is defined in various places in the 3GPP specifications, such as for example 3GPP TS36.423 which defines the interface between the cells.
FIG. 1 illustrates the two types of cell users. FIG. 1 illustrates two cells 10 and 11. Those users located in regions 12 and 13 can be classified as Cell Centre Users (CCUs) and those users located in regions 14 and 15 can be classified as Cell Edge Users (CEUs) as they are likely to suffer interference from the neighbouring cell.
When ICIC is implemented, the CEUs are restricted to a specific range of resource blocks. Cell edge users in neighbouring cells are restricted to different ranges in order to avoid conflict. Depending on the scheduling algorithm that has been used, this may result in CEUs which have been allocated a high priority being unable to be allocated resource blocks since the resource blocks available are restricted. Accordingly, when the network may be required to provide a certain QoS, the CEUs do not have the necessary resource blocks available to meet the guarantees required by that type of traffic.
Additionally, according to the conventional algorithms, once ICIC is implemented, the CEUs are allocated resource blocks within that specific range before any consideration is given to the rest of the users. In this way, when the network may be required to provide a certain QoS, the CCUs which have been assigned a high priority may not be allocated sufficient resources since the available resources have been allocated to the CEUs which may not have a high priority assigned.
The present invention seeks to overcome the above drawbacks with known resource block allocation using inter-cell interference coordination and QoS.